1. Field of the Invention
This invention relates to reactors for processing liquid-containing reaction mediums. In another aspect, the invention concerns polycondensation reactors used for melt-phase production of polyesters.
2. Description of the Prior Art
Melt-phase polymerization can be used to produce a variety of polyesters, such as, for example, polyethylene terephthalate (PET). PET is widely used in beverage, food, and other containers, as well as in synthetic fibers and resins. Advances in process technology coupled with increased demand have led to an increasingly competitive market for the production and sale of PET. Therefore, a low-cost, high-efficiency process for producing PET is desirable.
Generally, melt-phase polyester production facilities, including those used to make PET, employ an esterification stage and a polycondensation stage. In the esterification stage, polymer raw materials (i.e., reactants) are converted to polyester monomers and/or oligomers. In the polycondensation stage, polyester monomers exiting the esterification stage are converted into a polymer product having the desired final average chain length.
In many conventional melt-phase polyester production facilities, esterification and polycondensation are carried out in one or more mechanically agitated reactors, such as, for example, continuous stirred tank reactors (CSTRs). However, CSTRs and other mechanically agitated reactors have a number of drawbacks that can result in increased capital, operating, and/or maintenance costs for the overall polyester production facility. For example, the mechanical agitators and various control equipment typically associated with CSTRs are complex, expensive, and can require extensive maintenance.
Thus, a need exists for a high efficiency polyester process that minimizes capital, operating, and maintenance costs while maintaining or enhancing product quality.